package sort;

import sort.util.RamdomUtil;

/**
 * Created by asus on 2017/10/8.
 */
public class MStest
{
    public static void sort(int []arr)
    {
        int []temp = new int[arr.length];//在排序前，先建好一个长度等于原数组长度的临时数组，避免递归中频繁开辟空间
        sort(arr,0,arr.length-1,temp);
    }

    private static void sort(int[] arr,int left,int right,int []temp)
    {
        if(left<right)
        {
            int mid = (left+right)/2;
            sort(arr,left,mid,temp);//左边归并排序，使得左子序列有序
            sort(arr,mid+1,right,temp);//右边归并排序，使得右子序列有序
            merge(arr,left,mid,right,temp);//将两个有序子数组合并操作           
        }

    }
    private static void merge(int[] arr,int left,int mid,int right,int[] temp)
    {
        int i = left;//左序列指针
        int j = mid+1;//右序列指针
        int t = 0;//临时数组指针
        while (i<=mid && j<=right)
        {
            if(arr[i]<=arr[j])
            {
                temp[t++] = arr[i++];
            }
            else
            {
                temp[t++] = arr[j++];
            }
        }
        while(i<=mid)
        {//将左边剩余元素填充进temp中
            temp[t++] = arr[i++];
        }
        while(j<=right)
        {//将右序列剩余元素填充进temp中
            temp[t++] = arr[j++];
        }
        t = 0;
        //将temp中的元素全部拷贝到原数组中
        while(left <= right)
        {
            arr[left++] = temp[t++];
        }
    }
    public static void main(String []args)
    {


       int[] arr= RamdomUtil.generateRandomArray(10);
       
        long start = System.currentTimeMillis();//获取开始时间
        sort(arr);
        long end = System.currentTimeMillis();//获取结束时间
        for(int x:arr){
            System.out.print(x+ " ");
        }
        System.out.println();
        System.out.println("runningtime is :"+(end-start)+"ms");
        //System.out.println(Arrays.toString(arr));
    }
}